Geology and Natural History. 429 



five and one-half miles from the crater. It was the discovery of 

 these iron masses in 1891 that first attracted attention to this 

 locality ; they have been usually named from the neighboring 

 Canyon Diablo. As is well Jcnown this meteoric iron has some 

 important characters which need not be recalled here. 



In addition to the iron, a unique feature of tlie locality are the 

 "shale balls," of which great quantities have been discovered ; 

 the largest of these weighs something over forty pounds. These 

 are generally rounded or globular disintegrating masses of 

 meteoric iron and nickel oxide, many of them containing solid 

 nickel-iron centers. They have more or less of a shaly structure. 

 The iron of these balls contains chlorine in small amount, which 

 is practically absent in the Canyon Diablo siderites and to this 

 their disintegration is attributed. The shale balls, except when 

 imbedded in the silica, oxidize to a hard compact iron shale, 

 though often leaving an iron nucleus. The meteoric mate- 

 rial exists not only on and near the surface but has also been 

 brought up by the drills, often in the form of small specks of 

 nickel-iron oxide, even from a depth of 680 feet below the 

 floor of the crater, that is about 1200 feet below the original 

 plain level. 



It is, doubtless, disappointing that thus far the drills have 

 failed to tind the main mass of the projectile which did such a 

 a tremendous work ; nor has it been located by experiments with 

 the dipping needle. We must, however, accept the decision of 

 the author, who says : "We are thus compelled to conclude that 

 the mass which made the crater, and which, as has been sug- 

 gested above, may have been the metallic head of a small comet, 

 lies in the bottom of it somewhere ; for if it was a compact 

 cluster of iron meteorites which made the crater — there is cer- 

 tainly a great deal of evidence in favor of this theory and none 

 against it — it would seem from the evidence most unlikely that 

 any considerable portion was expelled after the cluster had pene- 

 trated some 1100 to 1200 feet of limestone and sandstone strata. 

 When the metallic mass is found, it would seem probable that it 

 will be found to have partially oxidized, much after the manner 

 of the buried shale balls, in which event it would still possess 

 great commercial value. As yet we do not know where it is in 

 the large area covered by the crater, but I personally think it 

 probable that, in the form of a vast number of shale balls and 

 perhaps Canyon Diablo siderites lying more or less closely 

 together, most of it will be found far over in the southern or 

 southeastern portion of the crater, where no prospecting by the 

 drill has been done, and that some of it, if not the larger part of 

 it, will be found underneath the perpendicular cliffs which form 

 the southern wall." 



Mr. Barringer's memoir, of which only a brief account has been 

 given, closes with a bibliography of the subject, and is accom- 

 panied by a large number of fine plates, giving views of the crater 

 from different points, the masses of limestone rock thrown out 

 from it, and also many illustrations of the altered sandstone, the 

 shale balls and iron in their various forms. 



